Inclusion Criteria:

• Any patient for whom we are able to obtain consent prior to their procedure or after their procedure in the intensive care unit.
• Patient must have a PA catheter, or a CCO/Flo Trak for the procedure.
• Is presenting for a procedure in which CPB will be required.
• Is considered high risk for VS.
• Patient considered to be at high risk for the development of VS will be identified per the guidelines developed by Levin et al. This includes any patient:
  • With pre-CPB vasopressor requirement(s); or
  • On pre-operative ACE, or beta-blocker or calcium channel blocker therapy; or
  • With a euroSCORE > 6; or
  • Presenting for pericardiectomy, aneurysm surgery, LVAD surgery or heart transplant, CABG or valve surgery other than a single mitral valve repair.
• Has no contraindications to arterial line or PA catheter placement
• Patient must fall into the defined parameters below for the majority of measurements over a 30 minute period (ex: 3 out of 5 measurements or 6 of 10, etc.):
  • Develops high-dose vasopressors for 30 min or longer and refractory hypotension consistent with VS within 24 hours of coming off CPB;
  • “High-dose vasopressor” will be defined as:
    • Norepinephrine infusion ≥ 0.1 mcg/kg/min; and/or
    • Dopamine infusion ≥ 15mcg/kg/min; and/or
    • Epinephrine infusion ≥ 0.1mcg/kg/min; or
  • Norepinephrine equivalent infusion of ≥ 0.1mcg/kg/min.
  • “Hypotension consistent with VS” will be defined as:
    • MAP< 75 mmHg via arterial line monitor.
• Cardiac index > 2.3L/min/m^2 via PA catheter monitor.
• If at the time study drug arrives, the patient who previously met criteria has fallen out, they must once again meet requirements only one time before the drug is given.

Exclusion Criteria:

• Age < 18 years old.
• Known pregnancy or patients without a documented pregnancy test if not menopausal.
• Known prior anaphylactic or allergic reaction to B12a.
• CKD stage 4 or worse (GFR < 30 ml/min) before study drug administration.
• ECMO (extracorporeal membrane oxygenation) or IABP (intra-aortic balloon pump)prior to study consent and post cardiopulmonary bypass.
• Patients currently on cardiopulmonary bypass.
• Circumstance for which the safety of the patient could be jeopardized by continued adherence to the study protocol.

Eligibility last updated 1/11/22. Questions regarding updates should be directed to the study team contact.